Degradation of organic dyes by persulfate using liquor grain-derived N,P-codoped mesoporous carbon as metal-free catalyst

Exploring facile and available approaches for resource utilization of liquor grains is in high demand for the brewing industry. Herein, we demonstrate a one-step blending method followed by heat treatment to prepare N,P-codoped mesoporous carbons (P/NMCs) using liquor grains as the carbon source, nano-SiO 2 as a template, and KH 2 PO 4 as an extra phosphorus precursor. N 2 adsorption/desorption, Raman spectra, X-ray diffraction, Fourier transform infrared spectra, transmission electron microscopy, and X-ray photoelectron spectroscopy were used to characterize the textural properties and surface chemistry of P/NMCs. Results showed that the P/NMCs that were prepared with a larger amount of the phosphorus precursor demonstrated much higher catalytic activity for persulfate activation. The enhanced catalytic activity is ascribed to the relatively large specific area and the greater amount of active surface groups that are induced by N,P-codoping. Decolorization of organic dyes reached ∼95 % under a broad operating pH range (3.0–11.0). Quenching tests with different radical scavengers revealed that degradation of organic dyes was controlled by a surface-bound radicals process and not by a free radical pathway.